Patent GB-717684-A (GB)
Title: Circular knitting machine, fabric and method for making the same
IPC: D04B15/66
Filed: 1951-06-22
Abstract: 717,684. Knitting. INTERWOVEN STOCKING CO. June 22, 1951 [Sept. 9, 1950], No. 14918/51. Class 74 (2). The needles of a circular machine are individually operated by mechanism including an electromagnet for each needle and superimposed controls, one for selecting predetermined ones of the electromagnets to be energized and another controlling the sequence in which the selected electromagnets are energized to activate the selected needles. In the arrangement of Fig. 7, needles are lowered, to draw loops, by the action on levers 35 of cams 43 rotating with the yarn feeders and remained thus lowered until electromagnets 56 cause latches 51 to release the levers 35, which are then raised by springs 59. In the arrangement of Fig. 8, each needle operating lever 60 is connected by a link 67 to an arm 65. When an associated electromagnet 82 is energized a latch 73 allows a roller 70 to be projected by a spring 72 into the path of clearing cams on a cam ring 95. Consequent raising of lever 60 brings the tail 91 of a latch 89 against an adjustable screw 92 to release a slide 85 and allow a spring 88 to project a roller into the path of stitch cams 103 in an inner ring 44. Other cams on ring 44 engage the inner ends of levers 60, or additional butts on the needles, to lower all needles to a yarn receiving position in which the latter are protected by the sinkers, so that the yarn cannot accidentally get below them. The rollers 70 are re-set by the action on their end faces of other cams on the ring 95 and the slides 85 by the action of other cams on ring 44 on a roller 87. Any roller 70 corresponding to an unselected needle is raised by levelling cams on ring 95 to such a height as to release, but not to clear, the latch; hence, such needles hold their stitches. In Fig. 9, each needle may be moved up and down to knit by a pair of electromagnets 26, 25, armature 24, and lever 20, it being possible also to raise and level needles (e.g. for rib toptransfer) by cams on a ring 30, rotatable by a handle and co-operating cams on a vertically movable ring 29. The sequence of operations of the needles is determined by rotating arms bearing electrically connected brushes such as 126, 127, which wipe over slip rings 118 and contacts 117 on discs 111-115. The contacts may be arranged in one or two complete or part circles. The arms may carry pairs of brushes on members 136 which are rocked by the drag of their brushes, so that the leading brush is always the operative one. The sequence of operation may be varied by varying, under pattern control, the discs which are operative. A circle 208 of contacts, Fig. 23, may operate needle lifting magnets, and a circle 209, the lowering magnets, the arm 222 carrying the brush for the inner row being able to swing relatively to the arm carrying the other brush 220, between stops 223, 224, so as always to trail more than 180 degrees behind it. An additional switch or switches in each needle operating circuit, in series with the sequence selection arrangement, determines pattern selection. The mechanism controlling these switches may be a moving strip or sheet which is perforated or has magnetized and unmagnetized areas, or areas differing in opacity; or it may be a rotating drum 155 with removable pins 156 which close the switches 153. The drum racking mechanism may be disabled by means under control of the main pattern drum and an auxiliary pattern chain. Electromagnetic preselection of yarn guides 240 is provided. The yarn guides are arranged in groups, one group per feed, on an inverted cup 230 rotating with the needle cylinder. Yarn is supplied from cops on a holder 243 which rotates with the cup, except during reciprocatory knitting. The yarn guides are fulcrummed at 242 with their lower ends inside the needle cylinder, when inoperative, so that it is unnecessary to cut idle yarns, which merely float inside without intertwisting. The guides are rocked to operative position by jacks 257 having butts 258 at varying heights for engagement by overlapping ring segments 260 moved radially inwardly by the co-operation of cams which they bear with cams on rotatable rings 263. To pre-select a yarn guide, an appropriate pin in the upper end face of drum 155 engages a projection 314, to close one of switches 309-and energize a corresponding electromagnet. This, through wire 307, bellcrank 305 and latch 302 frees a ratchet 290 for rotation by a pawl 300, operated by a constantly rotating shaft 280 through eccentric 279, yoke 277, link 281, arm 275 and links 295, 293 and 292. Each step of the ratchet reverses the relative tilt of levers 285, 286, through pins 289 arranged in staggered relation on opposite faces of the ratchet and so, through springs 288, reverses the tilt of a shoe 274 so that a bar 270 is reciprocated to rotate the pre-selected ring 263 back and forth through a link 272. The head 230 may be lifted axially away from the needle cylinder by rotation of a handle and releasably retained in that position by a latch. In knitting a sock with a plain elastic top, elastic thread is fed to alternate needles at one feed and another thread to all needles at another feed, to form the selvedge S. Then, elastic thread is fed to, say, every third or fourth needle at one feed, and body thread to all needles at one or more other feeds to make the top. The elastic thread is then withdrawn and one or more courses of body thread only knitted. The patterned leg is knitted by reciprocation. During one back and forth swing one guide at each feed feeds yarn such as 335, for an overplaid line such as 330 or 331, to selected needles, the remaining needles being inactive and, during the next complete oscillation, the overplaid guides and needles are inactive and body yarn such as 333 and 334 is fed to those needles which form the diamonds. This sequence is repeated and body yarn is thus floated behind previously formed overplaid stitches, e.g. at 337. A yarn from one area may be knitted at selected stitches, such as 336, in an adjacent area. To form the heel, instep needles are idled, and narrowing is carried out until, say, a quarter of the needle circle is active. All heel needles with, if desired, one or more additional needles at each end, are then restored to activity for at least one complete back and forth swing, or the whole needle circle may be brought into operation and one or more courses knitted by reciprocation or round and round knitting. The active needles are now again reduced to the above minimum number and widening effected, during reciprocation, up to the desired width, the instep needles are thereafter rendered active, foot and sole knitted by round and round or reciprocatory knitting and the toe formed in the same way as the heel. Finally, several round and round courses are knitted to provide a looper's edge.